yup: compare field itself with another field

Question

I had

StartIntensity: yup.number(),
EndIntensity: yup
    .number()
    .when(
        "StartIntensity",
        (StartIntensity: number, schema: any) => {
            return !!StartIntensity
                ? schema.moreThan(
                        StartIntensity,
                        "Max should be > min"
                  )
                : schema;
        }
    ),

but I need something like that

StartIntensity: yup.number(),
EndIntensity: yup
    .number()
    .when(
        "StartIntensity, EndIntensity",
        (StartIntensity: number, EndIntensity: number, schema: any) => {
            return !!StartIntensity && StartIntensity !== EndIntensity
                ? schema.moreThan(
                        StartIntensity,
                        "Max should be > min"
                  )
                : schema;
        }
    ),

but code above doesn't work properly. Is there any possibility to make this work ot other ways to execute this validation?

Answer 1

In your case first argument of .when() should be an array of keys:

StartIntensity: yup.number(),
EndIntensity: yup
    .number()
    .when(
        ["StartIntensity", "EndIntensity"],
        (StartIntensity: number, EndIntensity: number, schema: any) => {
            return !!StartIntensity && StartIntensity !== EndIntensity
                ? schema.moreThan(
                        StartIntensity,
                        "Max should be > min"
                  )
                : schema;
        }
    ),

keys: string | Array

https://github.com/jquense/yup#mixedwhenkeys-string--arraystring-builder-object--value-schema-schema-schema

If the above code throws "Cyclic dependency" error (which I think it will), try the following code:

StartIntensity: yup.number(),
EndIntensity: yup
    .number()
    .when('StartIntensity', (StartIntensity, schema) => {
      return schema.test({
        test: EndIntensity => !!StartIntensity && EndIntensity > StartIntensity,
        message: "Max should be > min"
      })
    }),

Or you can also use the ref:

StartIntensity: yup.number(),
EndIntensity: yup
    .number()
    .moreThan(yup.ref('StartIntensity'), "Max should be > min")